I have a few indulgences that often trip me up when I'm on autopilot or otherwise compromised:
1. I often can't resist Trapping and other non-luxury non-philosophy tile improvement techs, delaying my NC and setting me back.
2. I often can't resist the farmer's gambit & go too light on archers and mega late in building roads.
3. Sometimes I get addicted to farm improvement spam, even though I know I need to mix in mines to match citizen growth with worker pace to ensure cities work improved tiles, and my cities end up inefficient. Other times, I will spend early worker turns on mine spam for settler production, then build 1 settler too many because I want to work all the mines while workers prepare the other unimproved tiles. From there, it is easy to settle 1 city too many before NC (usually in settler vs. settler fighting with a neighbor over the best spot) & ruin my entire game by missing NC timing by a mile.
4. Sometimes I'll compound the problems of a bad slow start by bee-lining libraries & trying to skip granaries & it never works because granaries are essential.
5. Like an Alzheimer's patient, every time I build a couple horses for self-defense I do well, and remember how worthwhile they are. As the next game hits classical, I've defaulted to a self-defense force of pure archer again. Also strange, I never forget them if I'm building up a balanced army for attack.
6. I often forget 'war roads' (offensive and defensive roads that aren't for city connections) altogether even though one extra river bridge can be worth 3 units or an entire city, and often is.
7. Lategame, I tend to over-do settlement waves at renaissance and post-ideology. When I look at excess happiness, it always supports fewer cities than I think it does.
8. I tend to keep allies long after I should disband them and consume their empire out of a sense of kindness & fairness. In vanilla Civ5, my first immortal victory occurred when I realized that I needed to be more of a jerk to win. In my first try on japan/lakes/epic, Monty DoWed and then everyone piled on. I deflected monty's huge army and conquered him in the counterattack, then snowballed through siam, sully, france with more momentum and mass promotions. -44 happiness was the only reason the conquering had to stop for a time. The Iroquis had been my ally for millennia and now were right next door. I sent my army to the other hemisphere to the vanilla artillery vs. artillery dance with wu zutian, eventually breaking through enough cities to win by attrition, then quickly devoured the weaker germany behind her. Meanwhile, the iroquis got an era and a half lead and started making spaceship parts. Unable to win peacefully, I was forced into the matchup of his mech with my artillery and lost everything, excruciatingly slowly. After a think about the game, I loaded up a previous autosave; Had I just took my 4 time DOF, ally for millennia to the shed out back and gave him the old yeller before fighting china, I'd have all his wonders and wouldn't have any difficulty winning from that point. After loading the autosave, his empire melted like warm butter in the belly of japan and I easily went on to win.
